Injection molding apparatus with integrated hot runner system

ABSTRACT

A hot runner injection molding apparatus includes a machine injection unit with a machine nozzle, a first machine platen fixed to the machine base, a second machine platen movable with respect to the first machine platen, a hot runner manifold having an inlet melt channel and a plurality of output melt channels, a plurality of hot runner nozzles associated with the manifold output melt channels, and a movable valve pin plate connected to a plurality of valve pins.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from German Patent Application No. 10 2011 116 053.5 filed Oct. 18, 2011, the contents of which are incorporated herein in their entirety.

FIELD OF THE INVENTION

The invention relates to an injection molding apparatus for injection molding of small and miniature plastic parts.

BACKGROUND OF THE INVENTION

In such machines, molten material is fed from the screw barrel of an extruder via a manifold sprue bushing in an inlet melt channel of a hot runner system and there in a plurality of output melt channels fluidically connected to and downstream from the inlet melt channel.

Such an injection molding apparatus is known from the brochure “männer micro-män 50” of Otto Männer GmbH, which is made available on the company website http://www.maenner-group.com and whose content is herein incorporated by reference.

Known injection molding machines have a first machine platen, fixed to the machine base and a second machine platen which is movable with respect to the first machine platen. The first machine platen has an opening for the machine nozzle of the machine injection unit. A mold plate is mounted on the surface of the first machine platen opposite to the second machine platen. A hot runner manifold with hot runner nozzles is mounted on the surface of the mold plate. Moving means for the actuators of the hot runner nozzles are often mounted on the mold plate or on the machine platen.

This construction shows a large area of contact between the machine platen and the mold plate and between the mold plate and the hot runner manifold which assists heat conduction between these components resulting in energy loss in the hot runner system and thermal expansion of the machine platen. Further, the actuation means of valve pins are located behind the hot runner nozzles which results in a lower precision in parallel actuation of the nozzles resulting from positioning of the actuators laterally next to the mold plate and hot runner system. A positioning of the actuation means behind the nozzles also results in the need of a long distance manifold sprue bushing and inlet melt channel respectively.

It is therefore the object of the present invention to provide an injection molding apparatus improving the specified drawbacks for producing high quality small and miniature plastic parts.

An injection molding apparatus improving at least some of the specified drawbacks is described in the German patent application DE 10 2011 116 053. The content of this application is also incorporated herein by reference.

SUMMARY OF THE INVENTION

To overcome these drawbacks a hot runner injection molding apparatus is proposed comprising a machine injection unit with a machine nozzle, a first machine platen fixed to the machine base, a second machine platen which is movable with respect to the first machine platen, a hot runner manifold having an inlet melt channel and a plurality of output melt channels, a plurality of hot runner nozzles associated with the manifold output melt channels, a movable valve pin plate connected to a plurality of valve pins, wherein the valve pins are associated with the hot runner nozzles at least one moving means for moving the movable valve pin plate between at least two positions, whereupon the valve pins are displaced between at least two positions relative to the valve seat of the hot runner nozzle to control the amount of a molten material injected into a mold cavity through the manifold and the hot runner nozzles. The first machine platen of the hot runner injection molding apparatus has a chamber within which the hot runner manifold, the movable valve pin plate and the moving means for moving the movable plate are arranged.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention is more closely described in the Figures, in which

FIG. 1 shows a schematic view an inventive injection molding apparatus;

FIG. 2 shows a view of an inventive machine platen of a first embodiment in cross section;

FIG. 3 shows a view of an inventive machine platen of a second embodiment in cross section;

FIG. 4 shows a more schematic view of the inventive machine platen of

FIG. 3 in cross section with a machine injection unit.

DESCRIPTION OF THE DRAWINGS

Reference is made to FIG. 1 and FIG. 2 which are described in more detail in the German patent application DE 10 2011 116 053.

FIG. 1 shows a micro injection molding apparatus 1 for manufacturing miniature molded parts 2 with a machine injection unit 3, a cooling station 4, a part removal station 5 and a heating station 6. The machine injection unit 3 has a machine nozzle 8 arranged at the machine platen 7 for feeding melt.

A first mold half 10 is connected to the machine platen 7. The first and second mold halves 10, 11 are moveable in an open-close movement. FIG. 1 shows an open position.

FIG. 1 shows a transposition system, with a closed transposition way 12 connecting at least one of the stations 3, 4, 5, 6. The second mold half 12 is movable along the transposition way 12, 13, 14, 15. Thereby the molded parts 2 can be handled at more than one station in parallel.

In FIG. 2 ist erkennbar, dass die Maschinendüse 8 über ein Heiβkanalsystem mit an dem ersten Werkzeugteil 10 angeordneten Eintrittsöffnungen 28 der Kavität 9 verbunden ist.

FIG. 2 shows a view of an inventive machine platen 7 of a first embodiment in cross section. Via a hot runner system, the machine nozzle 8 is connected to gates 28 of the cavity 9. The gates 28 are located at a first mold plate 10. The hot runner system is arranged in a chamber 29 of the machine platen 7. The hot runner system comprises a manifold 30, which has a melt inlet 31 facing the machine nozzle 8. The manifold 30 is connected via a hot runner 32 to a furcation 33. Further hot runner channels 34 lead from the furcation 33 to the gates 28. By means of a clearance the manifold 30 is spaced from the machine plate 7.

Within the manifold 30 heating elements 35 are arranged at the hot runner 32 leading from the machine nozzle 8 to the furcation 33 and a further heating element 36 is arranged for tempering the manifold 30.

Within each hot runner leading from the furcation 33 to a cavity 9, a hot runner nozzle 41 with a valve and a valve pin 37 are arranged. The valve pin 37 is axially movable and positionable against a valve seat close to the cavity 9.

The valve pins 37 are arranged in parallel to each other and are fixed to a movable valve pin plate 38 with their ends opposite to the valve seat. The movable valve pin plate 38 is arranged within a chamber 29 in the machine platen 7. With moving means 39 the movable valve pin plate 38 is movable relative to the machine plate in an axially direction of the valve pins 37. In this way the valves of the nozzles 41 can be opened and closed synchronously.

The moving means are positioned lateral next to the inner chamber 29 within the machine platen 7. The recesses for the moving means are located in an area of the machine platen 7 between the movable valve pin plate 38 and the mold plate 46.

FIG. 3 shows a view of an inventive machine platen 7 of a second embodiment in cross section. The hot runner system is arranged in a chamber 29 of the machine platen 7. The hot runner system comprises a manifold 30. By means of a clearance the manifold 30 is spaced from the machine plate 7.

At each hot runner leading from furcation 33 to a cavity 9, a hot runner nozzle 41 with a valve and a valve pin 37 are arranged. The valve pin 37 is axially movable and thereby positionable against a valve seat close to the cavity 9.

The valve pins 37 are arranged in parallel to each other and fixed to a movable valve pin plate 38 with their ends opposite to the valve seat. The movable valve pin plate 38 is arranged within a chamber 29 in the machine platen 7. With moving means 39 the movable valve pin plate 38 is movable relative to the machine platen 7 in an axially direction of the valve pins 37. In this way the valves of the nozzles 41 can be opened and closed synchronously.

The moving means 39 are positioned lateral next to the inner chamber 29 within the machine platen 7. The recesses for the moving means are located in an area of the machine platen 7 between the movable valve pin plate 38 and the mold plate 46.

FIG. 4 shows a more schematic view of the inventive machine platen 7 of FIG. 3 in cross section with a machine injection unit 3. The machine injection unit 3 has a screw barrel 44 with feeds molten material to an injection plunger 45 of a machine nozzle 8 which is positionable to the melt inlet 31 of the hot runner system of the injection molding apparatus 1.

The hot runner system comprises a manifold 30, which is connected via a hot runner 32 and hot runner nozzles 41 to gates of mold cavities. The hot runner system is arranged in a chamber 29 of the machine platen 7. By means of a clearance the manifold 30 is spaced from the machine plate 7.

At each hot runner leading to a cavity, a hot runner nozzle 41 with a valve and a valve pin 37 are arranged. The valve pin 37 is axially movable and thereby positionable against a valve seat close to the cavity.

The valve pins 37 are arranged in parallel to each other and are fixed to a movable valve pin plate 38 with their ends opposite to the valve seat. The movable valve pin plate 38 is arranged within a chamber 29 in the machine platen 7. The moving means 39 move the movable valve pin plate 38 relative to the machine platen 7 in an axially direction of the valve pins 37. In this way the valves of the nozzles 41 can be opened and closed synchronously.

The moving means 39 are positioned lateral next to the inner chamber 29 within the machine platen 7. The recesses for the moving means 39 are located in an area of the machine platen 7 between the movable valve pin plate 38 and the mold plate 46. 

What is claimed is:
 1. A hot runner injection molding apparatus comprising: A machine injection unit (3) with a machine nozzle (8); A first machine platen (7), fixed to the machine base; A second machine platen (12) which is movable with respect to the first machine platen (7); A hot runner manifold (30) having an inlet melt channel (32) and a plurality of output melt channels (34); A plurality of hot runner nozzles (41) associated with the manifold output melt channels (34); A movable valve pin plate (38) connected to plurality of valve pins (37), wherein the valve pins (37) are associated with the hot runner nozzles (41); At least one moving means (39) for moving the movable plate (38) with the valve pins (37) between at least two positions, whereupon the valve pins (37) are displaced between at least two positions relative to the valve seat of the hot runner nozzle (41) to control the amount of a molten material injected into a mold cavity (9) through the manifold (30) and the hot runner nozzles (41); characterized in that the first machine platen (7) has a chamber (29) within which the hot runner manifold (30), the movable valve pin plate (38) and the moving means (39) for moving the movable valve pin plate (38) are arranged. 